Punnett Squares Have limitations in predicting allelic frequencies

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Punnett Squares • Have limitations in predicting allelic frequencies especially in large populations mating

Punnett Squares • Have limitations in predicting allelic frequencies especially in large populations mating randomly.

Hardy- Weinberg Law • Allow scientists to determine whether evolution has occurred • If

Hardy- Weinberg Law • Allow scientists to determine whether evolution has occurred • If the distribution of genotypes matches with the Hardy- Weinberg equation, then the population is said to be in equilibrium, meaning the population is NOT evolving.

Practice What does the following letters represent in the Hardy- Weinberg equation? p= P

Practice What does the following letters represent in the Hardy- Weinberg equation? p= P 2= q= q 2 = 2 pq =

The Hardy- Weinberg Equation p+q= 1 P 2 +2 pq+q 2=1 Where : p=

The Hardy- Weinberg Equation p+q= 1 P 2 +2 pq+q 2=1 Where : p= frequency of dominant allele q= frequency of recessive allele P 2=percentage of homozygous dominant allele q 2=percentage of homozygous recessive allele 2 pq= percentage of heterozygous individuals

Sample problem • You have sampled a population in which you know that the

Sample problem • You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following: – The frequency of the "aa" genotype. – The frequency of the "a" allele. – The frequency of the "A" allele. – The frequencies of the genotypes "AA" and "Aa. "

Answer: You have sampled a population in which you know that the percentage of

Answer: You have sampled a population in which you know that the percentage of the homozygous recessive genotype (aa) is 36%. Using that 36%, calculate the following • • • q 2 -“aa”genotype ( given)= 36% q- “a ”allele frequency=. 6 or 60% p - “A” allele frequency=. 4 or 40% P 2 - (0. 4 x. 04)=. 16 or 16% 2 pq =2(0. 4 x 0. 6)=0. 48 or 48% Frequencies of AA and Aa=. 16 +. 48=0. 64 or 64%

Sample 2 • Within a population of butterflies, the color brown (B) is dominant

Sample 2 • Within a population of butterflies, the color brown (B) is dominant over the color white (b). And, 40% of all butterflies are white. Given this simple information, calculate the following: – The percentage of butterflies in the population that are heterozygous. – The frequency of homozygous dominant individuals.

Practice questions Show all work 1. The ability to taste PTC is due to

Practice questions Show all work 1. The ability to taste PTC is due to a single dominate allele "T". You sampled 215 individuals in biology, and determined that 150 could detect the bitter taste of PTC and 65 could not. Calculate all of the potential allele frequencies. 2. After graduation, you and 19 of your closest friends (lets say 10 males and 10 females) charter a plane to go on a roundthe-world tour. Unfortunately, you all crash land (safely) on a deserted island. No one finds you and you start a new population totally isolated from the rest of the world. Two of your friends carry (i. e. are heterozygous for) the recessive cystic fibrosis allele (c). Assuming that the frequency of this allele does not change as the population grows, what will be the incidence of cystic fibrosis on your island?

In a population that is in Hardy-Weinberg equilibrium, the frequency of the homozygous recessive

In a population that is in Hardy-Weinberg equilibrium, the frequency of the homozygous recessive genotype is 0. 09. What is the frequency of individuals that are homozygous for the dominant allele? q 2 = 0. 09, so q = 0. 3. p = 1 − q, so p = 1 − 0. 3 = 0. 7 AA = q 2 = 0. 49

In humans, Rh-positive individuals have the Rh antigen on their red blood cells, while

In humans, Rh-positive individuals have the Rh antigen on their red blood cells, while Rh-negative individuals do not. If the Rhpositive phenotype is produced by a dominant gene (A), and the Rh-negative phenotype is due to its recessive allele (a), what is the frequency of the Rh-positive allele if 84% of a population is Rh-positive? • q 2 = 0. 16; q = 0. 4 p = 1 − q, so p = 0. 6 = 60%